Category:

• Cholinergic Muscle Stimulant

Description:

• Facilitates transmission of impulses across myoneural junction by inhibiting destruction of acetycholine by cholinesterase

Indications:

• Curare antidote

• Diagnosis of myasthenia gravis

• Differentiate between cholinergic crisis and myasthenia gravis crisis

• Evaluation of treatment requirements in myasthenia gravis

Contraindications:

• Mechanical, intestinal, and urinary obstructions

Precautions:

• Pregnancy category C; ionized at physiologic pH, not expected to cross placental barrier or excreted in breast milk

• May cause premature labor

• Seizure disorders, bronchial asthma, recent coronary occlusion, hyperthyroidism

• Dysrhythmias, peptic ulcer, megacolon, poor GI motility, bradycardia, hypotension

Adverse Reactions (Side Effects):

• CNS: dizziness, drowsiness, headache, incoordination, seizures, sweating, paralysis, weakness, loss of consciousness

• CV: AV block, bradycardia, cardiac arrest, dysrhythmias, , syncope, hypotension, tachycardia

• EENT: blurred vision, lacrimation, miosis, visual changes

• GI: cramps, diarrhea, dysphagia, increased peristalsis, increased salivary and gastric secretions, nausea, vomiting

• GU: Frequency, incontinence, urgency

• MS: arthralgia, fasciculations, muscle cramps and spasms, weakness

• RESP: bronchospasm, dyspnea, laryngospasm, respiratory arrest, respiratory depression, increased tracheobronchial secretions

• SKIN: rash, urticaria

Dosage:

Administered IV/IM

• Adult: 

  • Diagnosis of myasthenia gravis: 

    • IV 1-2mg over 15-30 seconds, then 8mg if no response

    • IM 10mg; if cholinergic reaction occurs, retest after ½ hour with 2mg IM

  • Evaluation of treatment requirements in myasthenia gravis: 

    • IV 1-2mg 1 hour after PO dose of anticholinesterase

    • if strength improves, an increase in neostigmine or pyridostigmine is indicated

  • Differentiation of myasthenic crisis from cholinergic crisis: 

    • IV 1mg, if no response in 1 minute, may repeat

    • myasthenic crisis clear improvement in respiration

    • cholinergic crisis increased oropharyngeal secretions and further weakening of respiratory muscles (intubation and controlled respiration may be required)

  • Curare antagonist: 

    • IV 10mg over 30-45 seconds; may repeat; not to exceed 40mg

• Child: 

  • Diagnosis of myasthenia gravis: 

    • IV 0.04 mg/kg given over 1 minute followed by 0.16 mg/kg given within 45 seconds if no response

    • >34 kg IM 2mg

    • <34 kg IM 1mg

    • infant 0.1mg, followed by 0.4mg if no response, not to exceed 0.5mg

  • Evaluation of treatment requirements in myasthenia gravis: 

    • IV 0.04 mg/kg given 1 hour after PO intake of drug being used in treatment

    • if strength improves, an increase in neostigmine or pyridostigmine is indicated